function throttle(fn, gapTime) {
    if (gapTime == null || gapTime == undefined) {
        gapTime = 1500;
    }
    let _lastTime = null;
    // 返回新的函数
    return function() {
        let _nowTime = +new Date();
        if (_nowTime - _lastTime > gapTime || !_lastTime) {
            fn.apply(this, arguments) //将this和参数传给原函数
            _lastTime = _nowTime;
        }
    }
}
module.exports = {
    throttle: throttle
}
